Over the years many attempts have been used to clean and restore pipes in-place using various processes and various devices that involve moving heated air through the piping section or system. See for example, U.S. Pat. Nos. 7,160,574 and 7,517,409 to Gillanders, which is by the same assignee and includes a co-inventor of the subject invention; 5,950,6812 to Reimelt, 4,503,613 to Koga, and 5,007,461 to Naf.
Conventionally in the restoration or placement of a barrier coating to the interior of a pipe, heat is generally 1) added at the source of the air blower, 2) added at the suction/open end of the piping system when a vacuum is used, or 3) heating wires are inserted into the pipe.
Each of these techniques has presented challenges to the operator in controlling heat to the pipe sections. For example when wires are inserted there is difficulty in the wires navigating bends and intersections. When confronted with valves or other restrictions within a pipe, such as rust build up, wires may not be able to be inserted at all.
A heater connected at the blower may have to be located some distance to the actual pipe leaving the heated air subject to heat loss as it travels from the blower source to the pipe. The use of heaters associated with compressors as the heat generating source are also generally bulky and costly to operate.
In the presently applied processes, heated air is an essential component and is used in at least three stages of the process 1) drying the pipes, 2) heating the pipes for application of the barrier coating and 3) drying the barrier coating. Presently whether one pushes air into a piping system with a compressor or pulls air through with vacuums, typical heating devices are located at the air driver source i.e.: compressor or in the case of a vacuum working alone a heating unit may be installed at the main entry point to the piping system.
Various types of heating devices that usually have a compressor and similar types of generator components are typically located outside the building or at a distance to the pipe source. The physical locations of these exterior devices are also undesirable due to their size and noise and exhausting considerations. These types of units that are associated with heating and moving air are often large, bulky and typically fossil fuel driven.
Various drawbacks with prior art heating devices include:                1) heat loss while the air travels from source to the piping system        2) run up in costs when relying on the use of diesel or gas type fuels        3) limits to the heat achieved        4) limited control to the operator to adjust the heat for each piping section. For example, pipe sections may be located at varying distances from the source yet the heat generated is from one source and can be used to service multiple service points involving pipe sections of varying diameters and connections in varying distances form the source        5) The typical heat sources are over sized due to common usage of a single source of equipment during the various stages of the pipe restoration operation. One typically is using, for example, a compressor during the epoxy drying stage when in reality what is actually required is a source of low volume heated air flow. The same can be said for the initial drying stage, when one can economically set up and heat and dry the piping system with out the use of compressed air.        6) Lack of adjustable control of heat and air flow at each inlet/outlet.        7) Limited ability to independently adjust air flow and heat. Current techniques have a limited use of the primary air delivery source limiting it to a single application per phase of application.        
As referenced above, all of these systems do not adequately address the application and use of portable heating apparatus and techniques that permit the operator greater operational flexibility and operating efficiencies. Thus, the need exists for such an apparatus and application solutions.